Automatic train-control system



May 8, 1928. 1,669,265

F. J. SPRAGUE AUTOMATIC TRAIN CONTROL SYSTEM Filed Jan. 7. 1922 4 Sheets Sheet 1 WJTNESSE S.

A INVENZOR. 3W

May 8, 1928.

1,669,265 F. J SPRAGUE AUTOMATIC TRAIN CONTROL SYS'fEM Filed Jan. '7. 1922 4 Sheets-Sheet 4 Fig. 1

IN VEIY TOR. 7

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. in order to permit the 6 under the control of the traffic made effective after Patented May 8, 1928.

UNITED STATES PATENT OFFICE.

FRANK JULIAN -SIPRAGUE, OF NEW YORK, N. Y., ASSIGNOR TO CONTROL & SIGhIAL CORPORATION, OF NEW YORK,

SPRAGUE SAFETY N. Y.

AUTOMATIC TRAIN -CON TROL SYSTEM.

Application filed January 7, 1922. Serial No. 527,803.

This invention relates to the braking control of trams and is intended to operate in con connection with standard braking equipment, which is indicated herein merely by the conventional showing of a brake pipe. k is assumed to be divided into blocks, following block signal practice, and where a wayside signal is installed I preferably take advantage of certain circuits thereaccording to The desired control is efi'ected by means I of magnetic impulses imparted-to proper receivers on the locomotives from track mag which are conditions.

As shown, there is but one braking impulse received in each block, although of course there may be a plurality of such impulses; and in order that it may be most effective provision is made for an automatic change the automatic braking from one of light degree to one of heavy degree according to the train speed, but subject to neutralizing of the'automatic result within the limits of speed and manual braking.

Provision is also made for restoring the controlling relay by a reset magnet, but not for a release of the brakes, the latter being manual as in ordinary practice. However, train to advance close e home signal this reset magnet is entrance into the ad- Vance block, and hence is located near the beginning of and within an occupied block and controlled by the trafiic conditions in that block, but with a provision for delaying its action sufiiciently to permitvmaim taining the reset magnet active on clearing of signals until the train entering the block and responsible for the condition of the reset shall havepassed over it.

Generally speaking, therefore, the object of the present invention is to enforce speed control of a train in accordance with imnets distributed along the track up to th or emergency proper co-ordination of pulses received trol of ratus and delay in train movement.

In my application, Serial N 0. 315,880, filed August 7, 1919, for ethod of and apparatus for control of train movements, I illustrate a system of automatic train control in which the braking action of the train initiated by magnetic application track magnet and the latter only magnet after the reception of two consecutive track impulses in the same block; and

shown, a permanent magnet and the other an electro-magnet, the'circuits controlling all magnets being determined in the latter case by the condition of the block in advance of theone occupied by a train and as to establish opposing condiworking magnetic fields of the application and reset magnets for like trafiic conditions in that advance block.

In the patent application referred to there are shown in one arrangement three track magnets in each block, namely, a home application and a reset magnet controlled by the home relayof the next advance block,

trolled by the distant relay of the advance block. The condition of the home and reset magnet is therefore determined by the traf- 0 conditions in the block next succeedin that occupied by the train to be braked, while the condition of the caution track magnet is determined by the trafilc conditions in the second block in advance.

The object of this disposition of track magnets, which was designed to meet a specific trunk. line railway condition, was to initiate a primary brake application on approaching the caution signal of the block next in rear of an occupied block, followed at or beyond the home 6 if required by a secondary brake application at the critical point of that block and by a restoration or reset of differential relay conditions near the end of the block at a sufficient distance from such end as to permit another primary brake application before reaching the end of the block in case of necessity.

Two things, however, incident to railway practice may make a sometime departure from this arrangement of track magnets desirable. In all train operation it is desirable to avoid unnecessary stops, and where heavy trains are being moved against grade this avoidance is of the utmost consequence because of the difficulty often experienced in starting; in both cases it is also desirable not to interfere with schedules. It is, therefore, the common practice for an engineer, when a home signal is set against im, while getting his train under control to nose up as close as possible to the home signal, even at very low speeds, without stopping until the last moment, in the hope and exectation that the home signal will'change 1n time to permit safe entrance into the next block without the operating disadvantage of having been brought to a complete stop.

If the reset magnet is set back from the entrance of a block a sufficient distance to permit the use of an intermediate caution application magnet, as shown in the patent application referred to, the locomotive brake impulse receiver will have passed over it if the engineer noses up to the home signal, and when the latter clears and the locomotive proceeds it will be under control speed throughout the entire length of the advance block, which might seriously interfere with train schedules and track capacity.

To .meet this condition the operation of the reset track magnet should be delayed until the train has advanced into the clear block, and where induced current receivers instead of magnetic ones are used to have had time to have attained sufficient speed to insure suitable inductive response.

With the reset magnets thus set within the entrance to the advance block the engineer would be free to nose up to the home signal, and as soon as it cleared to proceed into the next block when the signal goes to cantion or clear, subject them to proper reset, and also, thereafter, to primary brake application in case the next block in advance is occupied.

It is clear, however. that if the condition of the reset magnet is determined by the presence of a train in its own block, instead of by another train or traffic conditions in the block in advance, it is essential that in order to prevent its reset receiver registering with an inactive instead of an active reset magnet when conditions permit advance there must be a. delay in the change of condition of the. reset magnet of sufficient time to permit the train procccdinginto a clear block to get past the reset while it is still active, that is, before the track relays of its block can change its condition. This delay action can be insured by suitable construction of the contacts controlled directly or indirectly by the regular track relay. or by the mechanical movements of the signal blades, or by a combination of both.

Instead of an electron'iagnot for restoring or resetting the differential relay I can use a magnetically short-circuited permanent magnet with a choking coil on the short circuit section, the choking coil being under control of the signal circuits, or a. permanent magnet not under signal control, as may sometimes be desirable.

Where a normally shortcircuited permanent magnet is used the existence of the magnetic short circuit is particularly conducive to a permanency of condition and length of active life of the permanent magnet, as is well known in the art, and since the magnetic short circuit path is a fixture instead of a movable keeper the possibly disturbin conditions set up where such is used are 0 course absent.

In the application for patent referred to the coming on of the secondary or emergency brake application always follows a service application, and only takes place, except as otherwise provided. on or after the receipt of two consecutive track impulses, the object being to normally maintain service and avoid emergency braking.

In the present application a departure is made from this practice, in that with a single track magnet impulse the character of braking, whether service or emergency, primary or secondary, is automatically determined by the co-ordination of train speed and manual braking. Automatic primary or service braking will follow the single track magnet impulse in the absence of manual braking for all speeds above a predetermined low speed. Where manual braking is effected at the time the impulse is received the permissive low speed is raised within limits in proporton to the manual braking; but automatic service braking is imposed as soon as the manual braking does not meet requirements in speed reduction. Automatic secondary or emergency braking, on the other hand, will follow the single tracle magnet impulse when the train is travelling above a predetermined maximum speed regardless of existing manual or auto matic application. In short, the shift from primary to secondary, or from service to emergency, braking is automatically selective, and in this way the train can be taken care of by a single track magnet impulse.

The accompanying figures are divided into three groups.

Figs. 1, 1", 2 and 3 illustrate the application of the invention to a railway having the track magnets operated by direct current on a normal clear system, that is, with the controlling circuit alive when the advance block is clear.

Figs. 4, 5 and 6 illustrate its application to a railway having the track magnets operated on a normal danger system, that is, with the controlling circuit alive only when the train enters a block and the advance block is clear.

Figs. 7, 8 and 9 illustrate in detail a comparison of the circuit arrangements for the vanced one block the reset magnet is not section on which are two three kinds of reset magnet when installed, for example, on a normal clear system.

The characteristics of the normal clear and the normal danger systems, as applied to the automatic signal systems in common use, arewell known to those. skilled in the art andneed no amplification herein.

In detail, applied to a three blocks, with the block in advance of the occupied block clear. i

Figs- 1 and 4 show a section of a railway covering four block track locomotives with two clear blocks between.

igure 1 corresponds to the showing of block 0 of Figure 1, save that the control circuit of the magnets 15 and 16 contain an additional contact controlled by the position of the semaphore, this with contact 14.

-Figs. 2 and 5 shows a like track section with the rear locomotive advanced one block, so that there is only one intermediate clear block.

Figs. 3 and 6 show the rear locomotive ad- :Eurther, so there is no clearblock between the two locomotives.

Fig. 7 is an enlarged diagram of the track circuits shown in Fig. 1.

Fig. 8 illustrates the circuit arrangement when a magnetically short-circuited permanent magnet, with a choking coil on the short circuit part, is used for the reset, in which case, it will be noted, the application and reset magnets are both nets, oppositely conditionedtthe application magnet having an always open or air magnetic circuit, with a deflecting or neutralizing coil in the path of the working magnetic field, while the reset magnet has a normally closed or iron short-circuited mag netic field, with a choking coil to oppose; this shirt circuiting when contact being in series it is desired to have the field of the permanent magnet active.

.Fig. 9 illustrates a simplification of circuits, in that the delay relay is omitted, and under signal control. Fig. 10 is a diagrammatic illustration of an alternative control of the track magnets. active condition of the magnet field Fig. l-shows the invention as on a normal clear systemand permanent mag-- "ceding block, and hence it above a track magnet is shown by solid shading and the absence of an active field by the absence of shading.

Referring to Fig. 1, the track section shows three blocks, A, B and C separated by insulation 47. Each block has a local battery indicated at 10, at its far end, normally energizing a track relay H, which is main tained active whenever the block is clear. Relay H controls two contacts 11 and 12, the lower of which is used for signal purposes and need not be here further considered, while the u per one completes circuit through battery 3 and relay M, the latter when active making circuit through armature 14, which in turn completes circuit through battery 13 and the application and reset magnets, 15 and 16, located in two adjacent blocks.

The application magnet is of the compound type already described in my prior application, and consists of a permanent magnet with a fixed flux divided between soft iron stabilizing poles and working poles, with neutralizng coils interposed between the permanent magnet and the working poles.

This magnet is situated so as to give a braking impulse to the apparatus carried on the-locomotive at a proper distance from the end of the block. The reset magnet, which as above stated, may be an open permanent magnet, or an electro-magnet, or an iron short-circuited permanent magnet with a choking coil, is shown in the figure under consideration'asv an eleotro-magnet and it is situated near the beginning of the following block and hence controlled by the traflic conditions within its own block instead of those in the block in advance.

As in the former application, the applition and the rest magnets are differently disposed, in this case at right angles to each other, and both in the center line of the track, so as to properly register with the flux collecting receivers of the magnetic type shown empirically on locomotive L by 17 and 18. Of these, 18 registers with the application magnet 15, and 17 registers with the reset magnet 16. a

The reset magnet being Within the occupied block, if of a type under signal control,

has its condition determined by the traflic conditions within that block, practically coincident with the determination of the conditions of the application magnet in the prefollows that un less provision is made to delay the change in its condition when a locomotive enters its block that very entrance will make the reset magnet inactive and hence not in condition to restore the relays governing the train controlling apparatus-on the locomotive when its block has been cleared by the locomotive in advance.

" scribed is to place This is a condition incident to the setting forward of the reset magnet so that it will always be then clear for its corresponding locomotive impulse receiver no matter how closely the locomotive may nose up to the home signal. Various provisions may be made for establishing the necessary delay in change of condition in the reset magnet.

One method is to provide a dash pot 19 which delays the drop of armature 14 of relay M, and likewise to provide on armature 14 a follow up contact. With this arrangement it will be noted thatalthough contact 11 on relay H will drop promptly as the forward wheels of the locomotive enter a blockthe contact 14 on relay M, controlled by relay H, will be delayed in opening, insuring a corresponding delay in the cutting off of current in the circuit of reset magnet 16. Such a control is illustrated for example in block D of Figs. 1 and 4.

Another method of efiecting the necessary delay is to shunt the contact oi? armature 14 by contacts operated by the signal blade N, in which case it will require the opening of both sets of control contacts to change the conditions of the track magnets, and as' the blade drops not suddenly but leisurely a delay can be efiected by this arrangement even if the dash pot 19 is omitted. Such a control is indicated for example in block B of Figs.

1 and 4, the shunt to the semaphore con-.

tacts being shown in dotted lines.

An alternative of the last method just dethe semaphore contacts in series with the contact 14, so that the neutralizing or deflecting coils of the application magnet 15 will be .deenergized and an active field above the magnet created when the semaphore blade goes to stop position independently of the contact 14 A dual control is thus established for the track magnets which obviously has its advantages. Such a control for example is illustrated in block C of Fig. 1

Referring now to Fig. 1, where there are shown four blocks, A, B, C, and D with two clear blocks i ntermediate two locomotives it will be noted that the control circuit of the application magnet 15 in block C and the reset magnet 16 in block D is open at contact 14 because the presence of locomotive L in block D has dropped the contacts of relay H and hence deenergized relay This circuit has not been opened instantly on the' entrance of locomotive L. into block D, but has taken place with a delay in time which will have permitted the reset impulse receiver on locomotive L to pass over and clear of the reset magnet.

Under the normal conditions of railway operation this delay has not, however, been SllfllClEIltto have prevented the establishment of an active field condition over application magnet 15 to protect a train following locomotive L, but if it is deemed necessary to quicken this action relay M may operate two contacts, one of which will provide a delay action to control the reset magnet and the other a quick action contact to control the application magnet; or the latter can. be controlled directly through a contact on relay H, all as illustrated 1n Fig. 10 later to be referred to.

In Fig. 2 locomotive ,L is shown advanced into block B, where, because the next advance block is unoccupied, it finds application magnet 15 already cleared by the neutralizing coils, while the reset in the next block in advance is active.

' In Fig. 3 the locomotive intoblock 0, immediately in the rear of that occupied by locomotive L It will find the condition in this block just reversed from that shown in block B in Fig. 2, that, is, the control circuit of the track magnets having been opened track magnet 15 in its own block will be active and the reset magnet 16 in the advance block D will be dead.

Figs. 4, 5 and 6 each show the corresponding conditions on a normal danger track magnet system. In these, the circuit controlling the track magnets has an additional loop which is carried through the bottom contact 20 of delay action relay M, so that when locomotive L enters into a block, for B in Fig. 5, contact 20 of relay L has advanced M at the beginning of the next clear block, will be closed. This will establish a neutralized clear condition at application magnet 15 in block B and an active condition in reset magnet 16 in block C.

As. locomotive L enters into the next block C, as in Fig. 6, so that there is no clear block intervening between it and the block occupied by locomotive L, the circuit at contact 14 of the relay group controlled by the advance block D in which locomotive L is situated being open the circuit of the controllin track magnets 15 in block C and 16 in bloc D will be likewise open, leaving the said application magnet 15 in a brake applying or active condition and the said reset magnet 16 in an inactive condition.

In Fig. 8 the reset magnet 21 is a permanent magnet, similar to the application magnet 15, except that instead of there being an open air gap between the poles, as for example between the stabilizing poles of magnet 15, these poles are joined so as to make an iron short circuit path 22 for the flux in the permanent magnet; and on this portion of the iron magnetic circuit is wound a choking coil 23 which is under the control of the traffic conditions of its own block.

Under the conditions shown magnet 15 is neutralized, so that there is no active working field, whilethe flux through the magnetic short-circuit 22 is choked back by coil 23 and the magnetic flux of the permanent magnet 21 is given an air path in the wake referred to and in the alternative to contact of the reset receiver on the locomotive.

Failure of current in the control circuit permits the restoration of the magnetic short circuit, with simultaneous disappearance of the active field above the working poles of the magnet 21.

This construction has the advantage, more especially when operated on the normal danger control circuit plan, of maintaining the life of the permanent magnet.

In Fig. 9 there is no signal control of the reset magnet 24, but it is similarly positioned with reference to the .block as are the reset magnets in the other figures.

In Fig. 10 is illustrated a modified control of the track magnets in that the control coils thereof are in shunt to one another rather than in series as in the previous figures. Here the energizing coil controlling the reset magnet 16 has its'battery circuit completed through the delay action contact 14 of relay M as before, but the circuit of the neutralizing or deflecting coils of the application magnet 15 is contact 25 of the said relay, which contact is opened immediately upon deenergization of relay M following deenergization of the track-controlled relay H. There is indicated as alternative control for the said neutralizing or deflecting coils bymeans of lead 26 shown in dotted lines which is an 25, which would then be left out, and hence throws the control solely upon contact 11. As stated above, this arrangement obviates any delay in the response of the application magnet 15 to track conditions, while preserving the desired delay in maintaining the active field of the reset magnet 16.

Locomotive equipment and circuits.

These are shown diagrammatically and empirically in normal condition, but in view of the disclosures in my application already art both the equipment and its functioning can be made clear without physical details.

The equipment includes two normally energized electro-magnets, P and Q, which normally close the openings to atmosphere of brake pipes Bp-Bp, that controlled by magnet P having a restricted outlet and that by magnet Q, afull opening, so as to differentiate the character ofthe braking effected when magnets P and Q are de-energized service and emergency respectively. The current for these coils is supplied by battery U, which also supplies current for a normally energized relay 0.

Relay 0 on the one side directly connect ed with the battery U, has a stick contact 43 which engages armature 25, completing completed through the circuit of relay 0 to the other side of battery U through conductor 36, the normally closed contact of arm 34 on a compound magnetic receiver 17-18 and switch V. This relay 0 also has another circuit independent of stick contact 43, namely, through conductor 37 to the top contact of the normally retracted arm 33 of the magnetic receiver and thence through switch V to thebattery.

Relay 0 also controls two other armatures, 26 and 27, normally engaging contacts 42 and 41 in the circuits of the coils of magnets P and Q, respectively.

Referring nowto the service brake-controlling magnet P, it will be noted that on the one side it is directly connected with the battery U, and that on the other side it has two parallel return paths to battery, one through contact 42, armature 26, brush 29, the contact cylinder of governor R, line contact brush 28 and switch V and the other through movable brush 45, the governor contact cylinder, line contact 28 and switch V.

In a somewhat similar manner, the emergency brake-controlling magnet Q is directly connected with the battery U on one side, and on the other side completes its return circuit through lead 40 by two parallel paths, one through contact 41, armature 27 and switch V, and the other through contact brush 30, the contact cylinder of governor R, brush 28 and switch V.

The speed-brake governor is the same in principle as illustrated in my previous patent application, and consists of a centrifugal speed responsive member S which is attached to a longitudinally movable cylinder formed of two parts, the one with which the brushes are shown in contact being of metal and hence a conductor and the other 46 being of insulation. As the speed is increased the contact cylinder is moved to the left, as indicated by an arrow.

Besides the three brushes 28, 29 and 30, this contact cylinder has in engagement therewith, as above pointed out, another brush, 45, which is movable in the same direction as is the c linder by pressurefrom the locomotive rake system delivered through pipe 44 into one side of a springopposed piston in cylinder T. This contact in its normal position, i. c. with brakes 05, determines the low speed limit as that represented by the speed at which the conduc tive portion of the cylinder R breaks contact therewith, contact 42 being broken as a result of a track application impulse.

The limit of travel of brush 45 is such that it can finally only come to a position opposite to that of fixed brush 30, which corresponds to the highest speed from which a train can be braked in the required distance by a manual service application, and

coil Q with contact when in this position a further left-hand movement of the cylinder will break circuit on contact brushes 30 and 45 simultaneously. The cylinder of the speed governor can, however, travel further than this, in fact until it breaks contact on brush 29, set for the maximum permissible speed, which, it is apparent, is enforced independently of initiation from the track.

From the above it will be seen that there is here a combination of speed-responsive and brake-responsive devices which act in co-ordination to determine the conditions under which contact will be broken by brush 45, as well as providing for fixed speed limits at brushes 29 and 30.

Under the conditions shown in the diagram, that is, with the speed at the low limit, the breaking of the circuit of relay 0 at arm 34 on the receiver with the consequent dropping of armatures 27 and 26 to open contacts 42 and 41 will not result in automatic braking, even although the relay 0 remains deener ized until its circuit is restored through t e conductor 37 by reset contact arm 33. So long as the speed of the train is kept at the low limit the service brake controlling coil P with contact 42 broken as above will be energized through its path parallel thereto embracing the brush 45; and the emergency brake controlling 41 broken will be energized through its path parallel thereto embracing the brush 30.

The functioning of these various parts may now be described under the head of Operation of locomotive equipment.

As already indicated, the normal condition in the compound magnetic receiver 17-18 is with contact arm 34 closed and contact rm 33 open, the former being designated as the application contact and the latter as the reset contact. Whenever the longitudinal part 18 of the receiver passes through the field of a live application magnet 15, the traffic conditions for example being as shown in block C, Figs. 1*- to 6, the contact at arm 34 will be broken, de-energizing relay 0, when maintaining arm 25 will drop and open stick contact 43; and whenever the transverse part 17 of the receiver passes over a live reset magnet 16, as shown for example in block C Figs. 1 2 and 5, contact arm 33 will close contact to circuit conductor 37 and will re-energize relay 0 (if deenergized as just stated), causing arm 25 to pick up and close stick contact 43.

As already explained, relay magnet 0 controls arm 26, which when it drops opens one path of the return circuit of magnet P at contact 42, and also arm 27, which when it drops opens one path of the return circuit of magnet Q, at contact 41.

As shown, when the speed control contact cylinder moves to the left it first opens contact 45, then 30, and finally 29. These contacts may be designated respectively: 29, high speed contact; 30, maximum service limit contact; and 45', variable service limit contact.

So long as contacts 42 and 41 arevclosed the circuit of magnet Q, can not be opened by the speed mechanism, because although contact 30 may be broken the parallel return circuit will be completed through contact 41 and arm 27, but the circuit of magnet P having one path opened at contact 45 at medium or low speeds may have its remaining path opened at the maximum speed brush contact 29.

In normal operation the cylinder contact controlled by speed responsive member moves back and forth with every corresponding change in speed of the train, and likewise contact 45 moves to and fro according to the amount of braking pressure delivered to its control cylinder through pipe 44, but it is limited in its left-hand movement to the position occupied by the fixed brush 30 in the circuit of magnet Q.

If, now, the locomotive is operated at any speed below that which will break contact '45 the de-energization of relay 0 and the safe braking at the then speed of the train to prevent the opening of circuit of magnet P and the automatic coming on of the service brakes.

Since contact 45 is limited in its left-hand movement it follows that this optional control of the circuit of magnet P is limited, so far as manual braking is concerned, to speeds which do not exceed the maximum permitted for service braking, and above this speed the service brakes will come on at all times when relay 0 is deenergized by the opening of the receiver contact 34; and the circuit of magnet P though closed at contact 42 will also be opened whenever the speed reaches'the point indicated by brush 29, regardless of whether manual brakes have been applied or not.

It will be further noted that up to .the speed indicated by the position of brush 30 magnet Q, will have remained energized even if contact 41 be opened, but if this contact is open when the breaking contact edge of the conductive portion of the governor reaches the position indicated by brush 30 the circuit 0 magnet Q, will also be broken and the secondary or emergency brake will come on. I

From the above it will be seen that there is herein provided, on the receipt of a single track impulse and with a single opening of the application receiver contact 84, a dual kind of brakingprimary or service and secondary or emergency-which automatically comes on according to the co-ordinated relations of speed and manual braking so far as the service brake is concerned and only above the maximum service condition so far as the emergency brake is concerned; and service brake protection is likewise afi'orded, without regard to the opening of the relay 0, whenever the speed reaches any predetermined maximum. I

Or, to put it another way, service braking is provided at agiven maximum speed, and also whenever on or after thereceipt of a track impulse the train speed exceeds the proper co-ordinated condition of speed'and braking, while below a certain speed there is no service braking whatever; and further,

that an excess speed alone will not causeemergency braking, nor does emergency braking take place below the maximum possible service braking co-ordinated speed, while the shift of control from service to service plus emergency braking is automatic.

On the approach to dangerous curves or crossings, where track magnets may be installed not under signal control, for example as shown-in Fig. 9'respecting the reset magnet 24, with due regard to orientation to register with the application impulse collectors on the receiver, a careless or inattentive engineer will get service or emergency braking as the case may demand.

The word train is used herein in its broad sense to indicate one or more Vehicles travelling upon rails.

The foregoing details have been given for clearness of understanding, and no undue limitation should be deduced therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

Having thus fully described my invention, what I claim as new and desire to patent is, the following:

1. In an automatic train control system, in combination Fa vehicle, a track for said vehicle divided into track circuit blocks, a train control apparatus carried on the vehicle and initiating and restoring devices on the vehicle for governing said train control apparatus; a permanent magnet associated with'each block for initiating the operation of the control device, coils active working field of said permanent'magnets and a controlling circuit for said coils controlled by the block next in advance; an electro-magnet in the rear of the permanent magnet in each block controlled by the trafiic conditions within its block, operating when energized to restore said train control appaown block,

for nullifying'the' ratus to its initial condition and means for delaying the deenergizing of said magnet.

2. In an automatictrain control system for railroads having tracks divided into blocks each provided with a normally closed track circuit, automatic train control apparatus on a vehicle adapted to be put in operaating condition to control the movement of the'vehicle and to continue in such condition until reset, a relay on the vehicle for conditioning said apparatus and for resetting it and impulse receiving means on the vehicle controlling said relay; a permanent magnet on the track in each block, said magnet being adapted to co-operate with the im pulse receiving means to condition the train control apparatus, operating coils associated with each permanent magnet and adapted when energized to render it inefi'ective to influence the impulse receiving means, an energizing circuit for the coils of each permanent magnet controlled by the track circuit next in advance of the corresponding block; and an electro-magnet in the rear of the'permanent magnet in each block for influencing the impulse receiving means and to cause resetting of the train control apparatus, an energizing circuit for each electromagnet controlled by the trafiic conditions within its own block, and means for delaying the deenergizing of said magnet.

3. In an automatic train control system for railroads having tracks divided into blocks each provided with a normally closed track circuit, a permanent magnet on the track in each block and having coils associated therewith for neutralizing its Working field, an electro-magnet in the rear of the permanent magnet in each block, an energizing circuit for the coils of the permanent magnet controlled by the trafiic conditions of the block next in advance, an energizing circuit for the electro-magnet controlled by the traflic conditions within its normally energized brake control apparatus on the vehicle, a normally closed control circuit for said apparatus, a normally energized stick relay on the vehicle'controlling said circuit, impulse receiving means on the vehicle actuated by the magnets on the track, a stick said relay opened when the impulse receiving means is influenced from the track by a permanent magnet, a picleup circuit for the stick relay. governed by th net and means for delaying the deenergizing of the said electromagnet.

4. In an automatic train control systen'r for railroads, having tracks divided into blocks [each provided with a normally closed track circuit, a normally energized brake control apparatus on a vehicle, a normally energized relay acting to govern said apparatus, impulse receiving means on the vecircuit of the e electro-mag-v hicle controlling said relay,

a permanent magnet and an electromagnet associated with eachblock and adapted to influence the impulse receiving means, means associated with each permanent magnet controlled by'the traffic conditions in the advance block for rendering it ineffective to influence its receiving means, means controlled by the circuit of the occupied block for energizing the elec'tromagnet of its own block and means for delaying the deenergizing ot' said magnet.

5. In an automatic 'train control system, combination: a vehicle, a track for said vehicle divided into track circuit blocks, train control apparatus carried .on the vehicle, an initiating control device and restoring control device on the vehicle for governing said train control apparatus, an open circuit-ed permanent magnet associated with each block for operating said initiating control device, coils for nullifying the active working field of said permanent magnet, a controlling circuit for said coils controlled by the trafiic conditions in the advance block, and apermanent magnet in each block with its poles magnetically short-circuited with a choking coil on such short circuit section and operating when energized to con trol said restoring control device on the vehicle to restore said train control apparatus to its initial condition.

6. In an automatic train control system for railways having tracks divided into blocks, each provided with a normally closed track circuit, automatic train control apparatus on the vehicle adapted to be put into condition to control the movement of the vehicle and to continue in said condition un- .til reset, a relay on the vehicle for conditioning said apparatus and for resetting it, impulse receiving means on the vehicle controlling said relay, a permanent magnet on the track in each block adapted to co-operate with said impulse receiving means to condition the train control apparatus for operation, coils associated with each permanent magnet and adapted when energized to render it ineffective to influence the impulse receiving means, an energizing circuit for the coils of each permanent magnet controlled by the track circuit of the block next in advance of the corresponding block, a short circuited permanent magnet in each block for influencing the impulse receiving means to cause resetting of the train control apparatus, a choking coil for said short circuit and an energizing circuit for said choking coil controlled by traflic conditions.

.7. In an automatic train control system, the combination with a vehicle, of a train control apparatus carried therein, a relay for conditioning said apparatus, means for changing said relay from 1ts in t al cond tion, means for restoring the inltlal condi- (train, a relay mee aea air circuit and means under control of tratfic conditions for nullit'ying the magnetic field in one part, of the circuit, and permanent magnets metallicall y short circuited and with means under control of trafiic conditions for bucking the magnetic field in said short circuit.

9. In an automatic train control system, the combination with apparatus on the train for the control thereof, of vehicle carried means for controlling the actuation of said apparatus including two contacts, one normally open and one normally closed, and means along the track differently controlled by' diilerent traffic conditions, to respectively shift the said contacts from their normal positions, said track means being reversely conditioned by the same track condition.

10. In an automatic train control system, the combination of control apparatus on the for initiating a brake ap lication having two control'branches, one eing through a normally open contact, and the other through a normally closed contact and a stick contact, and successive magnetic fields along the track, one of said fields causing the opening of the normally closed contact and another of said fields the closing of the normally open contact.

11. In a train control system comprising trackway elements under traffic control and a vehicle carried element registering inductively therewith to a relay responding to change in the magnetic ux of the couple when a danger condition exists ahead, brake initiating circuits controlled thereby to give a plurality of degrees of automatic braking, -and means depending upon the speed of the train to determine which degree of braking shall be effective.

12. In a train control system the combination of a traifie controlled trackway element and a vehicle-carried element registering inductively therewith, said two elements constituting a magnetic couple in an operatively active condition when a danger condition exists in advance territory, electro-responsive means having its normal condition changed when the said magnetic couple is rendered operatively active, brake initiating circuit-s controlled by the said electro-responsive means to initiate braking of varia- 13 form a magnetic couple, 110' the combination of means for effecting a;

service braking, separate means for effecting an emergency braking, a control device for selectively efi'ecting actuation of either of said means and means responsive to the braking of the train for governing the action of said control device.

15. In an automatic train control system, the combination of means for effecting a service braking, separate means for effecting an emergency braking, a control device for selectively actuating either of said" means, means responsive to the speed of the train and means responsive to the braking of the,

train which cooperatively govern the action of said control device.

16. In an automatic train control system, the combination of means for efiecting a service braking, se arate means for effecting an emergency bra ing, acontrol. device for selectively efiecting actuation of either of said means, means responsive to the speed of the train for governing the action of said control device, and means controlled by manual braking for varying the speed conditions under which automatic service brak-' ing is effected. 17. In an automatic train control system, the combination of means for eifecting a service braking, se arate means for effecting an emergency raking, a coil actuated from thetrack' for initiating the operation of said means, a control device for selectively efi'ecting actuation of either of said means subsequently to initiation by sald c011,.means responsive to the speed of the vehicle for governing theaction of saidcontrol device, means contrelled by manual braking for varying 'the sneediconditions under which automatic service braking is effected, and

means independent of said track actuation for effecting automatic service braking above a predetermined maximum speed.

18. In an automatic train control system, the combination of brake'applying means upon the vehicle, means along the track for creating magnetic fields for. imparting to the vehicle a braking impulse and a resetting impulse, common means for creating such impulses, means for actuating said common means, and'means for delaying the operation of the common means subsequent to opera- "pulse device,

cooperating magnetic tive change of co dition of the, actuating means;

19. In an automatic train control system the combination with a track divide into blocks, of an application impulse device, a. cooperating reset impulse device located in the block in advance-of the application immeans for oppositely effecting the operative condition under the controlot the said advance block,

and means for delaying the. change in the condition of the reset; impulse device.

20.; In an automatic train control system, the combination with a track divided into blocks, of'a magnetic application impulse device, a cooperating magnetic reset impulse 'device located in the block in advance of the application impulse device,

positely conditioning the active working fields of the said devices under the control of the said advance block, and means for delaying the change in the active working field of the reset impulse device.

of said devices means for op- 21. In an automatictrain control system I the combination with a track divided into blocks, of a magnetic application impulse device, means for nullifying the active Working field thereof embodying a coil, a reset impulse device located in the block in advance of the apdevice, means for effecting field therefor embodying the said coils including plication impulse an active working a 0011, a circuit for a battery'and a normally closed contact, control means for said circuit governed by traflfic conditions in the said advance block, and

means for delaying the opening of said contact.

22. In anautomatic train control system, the combination of means for effecting a service braking, separate means for effecting an emergency braking, a coil for initiating the operation of both of said means, a

control device for selectively e ifecting actuation of either ott said means subsequently to initiation by, said coil, and means actuated from the track for eifecting operation of the said coil and for-restoring the said coil to normal condition. r 23. In an automatic train control system the combination with a vehicle and a track divided into blocks, of vehicle carried means for effecting a service braking, separate means for efi'ecting an emergency braking, coil for initiating the operation of said means, a control device for selectively efiecting actuation of either of said means subsequently to initiation by said coil, an application impulse device located on the track for effecting operation of the said coil, a cooperating reset impulse device located on the track in the block in advance of the application impulse device for effecting re- 'storation of the said coil to normal condition, means for oppositely eiiecting the operative condition'of said track devices under the control of the said advance block, and

' means for delaying the change in the condifecting actuation *of either oflsaid means subsequently-to the initiation by said coil, a magnetic impulse receiver on the vehicle for determining the condition of said coil, a. magnetic application impulse device located on the trac for influencing said receiver to effect operation of said coil, a cooperating magnetic reset impulse device located on the track in the block in advance of the said application impulse device for influencing the said receiver to effect restoration of the said coil to normal condition, means for oppositely conditioning the active working fields of the said devices under the control of the said advance block, and means for delaying the change in the active Working field of the reset impulse device.

FRANK JULIAN SPRAGUE. 

